120V wall outlet that sometimes rises 127V is that OK.

Discussion in 'General Electronics Chat' started by codeman7, Aug 15, 2018.

  1. codeman7

    Thread Starter New Member

    Aug 15, 2018
    I have a 120V wall outlet that sometimes rises above 127V. Is that too high? This is a server room and a backup battery supply is plugged into the wall outlet and the servers are plugged into the battery backup. After about 5:00PM - 8:00AM I receive notifications from the battery backup that it is compensating for high voltage. In the configuration of that battery backup, high voltage is above 127. Should I be worried or should I increase the tolerance in the configuration so it isn't constantly sending notifications and compensating for the higher voltage?
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    Unless it's going to cause damage to your equipment, i would increase the level settings to prevent nuciance notifications.
  3. Reloadron

    Distinguished Member

    Jan 15, 2015
    The typical range for 120 VAC 60 Hz service in the US is +/- 5% of nominal so with 120 VAC nominal anywhere between 114 VAC and 126 VAC is normal. My residence in Cleveland, Ohio USA is about 248 VAC split phase pretty even at 124 VAC. I would not be concerned and would just raise the limit. Utility company voltage will vary depending on the time of the day, especial;ly in industrial compounds. ANSI C84.1 is the specification. I see Dodgydave posted as I type and I agree, I wouldn't worry about it unless it is well outside the UPS specifications for input voltage.

  4. WBahn


    Mar 31, 2012
    It might be a good idea to find out just how high it is going above 127 VAC, but if it is only going above it slightly and briefly, probably not a problem.
    ebeowulf17 and Reloadron like this.
  5. dl324

    AAC Fanatic!

    Mar 30, 2015
    I'd only worry about it if the voltage was high enough to damage the battery backup.
  6. ebeowulf17

    AAC Fanatic!

    Aug 12, 2014
    Yes, that's the key. If the system is simply reporting "over 127" then you don't really know yet how serious it is. Personally l wouldn't be worried about a few more volts, but if you don't know how much it's going above 127, then you should find out.